This application claims the priority of 199 09 141.2, filed Mar. 3, 1999, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a roof extension for a motor vehicle, and more particularly, to a roof extension having at least two roof members which, by way of fastening devices are mounted on the vehicle roof, and having guide rails arranged approximately in parallel to one another, along which a ladder can be displaced from a starting position into a transport position on the vehicle roof and can be fixed in its end position, for the sliding guidance, at least on one end of the ladder, laterally projecting guiding devices being arranged, and is the ladder, after the fixing is eliminated, being displaceable back into the starting position,
A roof extension for a motor vehicle is shown in U.S. Pat. No. 2,922,551. A roof carrier is indicated there whose horizontally extending rectangular frame is mounted by four fastening devices on the vehicle roof. On the bottom side of the frame, two guide rails are fastened which are arranged approximately parallel to one another and extend in the transverse direction of the vehicle along the guide rails, a ladder can be displaced from a starting position supported by the lower end on the ground into a horizontal transport position on the vehicle roof and can be fixed there in its end position. For the sliding guidance of the latter, two laterally projecting guiding devices are arranged on its upper end. After the fixing in the transport position is eliminated, the ladder can be slid back again into the leaning starting position.
It is a disadvantage of the roof carrier that the guide rails constructed as angle profiles have a considerable lateral distance from the supporting fastening points of the roof carrier. Because of this arrangement of the ladder, a considerable vibration of the entire roof extension may occur in the driving operation.
Another known roof extension is Japanese Patent Document described in JP 08-158768, in which the guide rails also extend at a considerable lateral distance from the supporting fastening points of the roof carrier.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.
An object of the present invention is to provide a roof extension having an improved vibration behavior during the transport of a ladder.
According the invention, this object has been achieved by a roof extension in which the guide rails extend close to the fastening points of the roof members, the guiding devices being held by laterally projecting extension arms of the ladder.
As the result of the laterally projecting extension arms which hold the guiding devices, the guide rails can be arranged close to the fastening points of the roof members. A fastening of the guide rails on the roof members can be provided so that the vibration of the ladder during the transport can be significantly reduced. If the ladder is used in a starting position fixed on the guide rails for the loading and unloading of a roof carrier, furthermore, the undesirable bending of the roof members can also be significantly reduced. The guide rails of the ladder and the roof members can extend side-by-side, preferably approximately parallel to one another, or transversely and approximately vertically. By way of the arrangement of the guiding devices on the extension arms, it is additionally possible to arrange the ladder on an already existing roof railing, for example, of a station wagon, in which case the guide rails would have to be provided on the roof members of the roof railing which preferably extend in the longitudinal direction of the vehicle. It would also be conceivable to use the roof extension according to the present invention as a secure transport possibility for a ladder which, in its starting position, can be used, for example, for workers at construction sites or in the household.
In an embodiment of the roof extension of the present invention a connection is established between the respective guide rail and the assigned roof member which has a particularly stable construction against a bending and against vibrations.
A one-piece construction of the roof member and of the respective guide rail can be produced in a particularly simple manner, in which case the guide rail can be matched particularly well with respect to its length and shape with the roof member.
In another embodiment, the roof extension according to the invention can be retrofitted in a particularly simple manner with guide rails for the arrangement of the ladder.
A ladder, which, by way of its upper end, is easily detachably fastened on the guide rails and, by way of its lower end, is supported on the ground, permits a secure and simple loading of a roof carrier or of a roof box and, in addition, can be removed in a simple manner when it is not needed.
If, in addition to the one end of the latter, laterally projecting extension arms and guiding devices are also arranged on the other end of the ladder, the ladder can be held above the roof by the guiding devices within the guide rails and must only be secured against a sliding out of the guide rails. In addition, the ladder can be slid into the guide rails and pulled out of the latter from opposite ends, so that the roof extension can be loaded on both sides.
In yet another embodiment of the roof carrier, the guiding devices, which already exist, each have a locking device which permit a simple fixing of the ladder.
A further development of the roof carrier permits an adaptation to the spacing of the guide rails which varies, for example, in the case of different vehicle models.
Because of their simple and maintenance-free construction, particularly sliding blocks were found to be advantageous for a use as guiding devices within the guide rails.
A ladder which is constructed in two or several parts can be adapted in a simple manner to the corresponding vehicle width, in which case a telescoping ladder also has a low wind resistance in the transport position.
The extension arms, which are formed by a continuous tube, not only have a relatively simple and stable construction, but, for a simpler loading of the roof carrier, the ladder can also be displaced along the tube.